This is a semester-long experimental study aimed at investigating the effects of a PBL (Problem-based Learning) approach on the English oral language performances of English major students in one of the private universities in Bangkok. For the purpose of the study, a systematic PBL model for English language classrooms was implemented. Furthermore, the subjects' opinions towards learning with the PBL approach were also explored through the use of questionnaires and interviews. The findings showed that the mean scores of the posttest were significantly higher than those of the pretest. Their English oral performances were more fluent and accurate. Moreover, they used varied sentence structures in addition to simple sentences. Additionally, the subjects' opinions towards learning with the PBL approach were discussed. [This article is reprinted with permission from "Enlivening EFL discussion classrooms with a problem-based learning approach" by Tanisaya Jiriyasin (2011), "E-Journal for Researching Teachers," Vol. 4, Chulalongkorn University Language Institute.]